Heat treated alloy steel



Patented Aug. 18, 3936 UNITED STATES PATENT OFFICE HEAT TREATED ALLOY sTEEL Peter Payson, New York, N. Y., assignor to Crucible Steel Company of America, New York, N. Y., a corporation of New .iersey No Drawing.

10 Claims.

ing tools, and more generally for use in articles requiring great strength, hardn ss and resistance to corrosion and oxidation at elevated temperatures.

10 In my application Ser. No. 6,645, filed February 15, 1935, for Letters Patent No. 2,009;9"l4, and in a division thereof, Ser. No. 33,795, filed July 29, 1935, of which this application is. a continuation in part, I have described a new heat and corrosion resisting steel and a method of treating the same whereby said steel may be hardened by said treatment up to C 65 Rockwell or more for certain analyses. The new steel, when so hardened, does not suffer any substantial permanent reduction in hardness after heating as high as 1400 or 1600 F. and in some instances to even higher temperal tures. It possesses a'degree of hardness at temperatures of 1100 to 1800 F. which is superior to that of steels previously known. It is, moreover, highly resistant to corrosion, oxidation and scaling at elevated as well as at atmospheric temperatures, including conditions prevailing in the exhaust passages of internal combustion engines operated by either standard or special fuel mixtures, such as the so-called anti-knock varieties.

In my patent referred to, the new steel is stated to contain as essential ingredients in addition to iron: about 18% to chromium, about 1% to 85 10% of a nickel-like metal, such as either or both -of nickel and manganese, about 1% to 10% of a molybdenum-like metal, such as either or both of molybdenum and tungsten, in proportions to render the steel initially ferritic, i. e., ferritic in 4 the "as rolled, as forged", as cast or as annealed" I condition.

Steel conforming to the information above set forth may, in accordance with a further aspect of the invention of my patent aforesaid, be hardened by heating to some temperature within the approximate temperature range of 1200 to 1800 F. for an interval required to secure a desired hardening, the most appropriate temperature, within the range specified, beingdependent on.

60 the particular'composition of the steel to be hardened.

Whereas, however, my patent aforesaid sets the upper limit for carbon at about 1.0%, I have found that steels otherwise conforming to my invention 5 but containing carbon considerably in excess of Application November 11, 1935,

Serial No. 49,163

1%, are, nevertheless, susceptible to substantial increases in hardness on heating. I conclude from my investigations that carbon may be present in such steels in amount up to about 4.0%

or more. 5

My patent aforesaid mentions only molybdenum andtungsten as appropriate for the molybdenum-like constituent of the new steel. I have. however, observed that as regards its effect on hardenability, silicon may be substituted in whole 1 or in part for the molybdenum-like metal as is evidenced by the following test data:

TABLEEFFECT on ST AND M0 0N HABDENABILITY C constant at .15% Ni constant at 4.75%. Cr 1 constant at 25%Hordness Rockwell "C" Steels otherwise conforming to the information above set forth but containing one or more of the elements cobalt, aluminum, copper and vanadium in aggregate amount up to about 5% may be heat hardened by the method indicated. Additions of one or more of these elements to the new steel are sometimes'desirable to increase the toughness, forgeability, etc.

From the foregoing it will be apparent that making a small allowance for impurities the quantity of iron in the steel may be as low as about 36% or as high as about 80% by weight of the total.

What I claim is:

1. An alloy steel which is hardened by heating within the approximate temperature range of 1200 to 1800 F., containing: about 18 to 35% 5 chromium, about 1 to 10% of metal of'the group consisting of nickel and manganese, about .5 to 10% silicon and about .5 to 10% of metal of the group consisting of molybdenum and tungsten, the content of silicon, molybdenum and tungsten aggregating about 1 to 10%, carbon up to about 4%, and the balance substantially iron in proportions to render said steel initially ferritic.

' 2. An alloy steel which is hardened by heating within the approximate temperature range of 1200 to 1800 F. and which is characterized by undergoing no substantial reduction in hardness after heating to temperatures as high as about 1400 F., said steel containing: about 18 to chromium, about 1 to 10% of metal of the group consisting of nickel and manganese, about .5 to

10% silicon and about .5 to 10% of metal of the group consisting of molybdenum and tungsten, the content oi'silicon, molybdenum and tungs en aggregating about 1 to 10%, not more than about 5% in aggregate of other steel alloying elements primarily for imparting other than heat hardening properties to the steel, carbon up to about 4%, and the balance all iron in proportions to render said steel initially i'erritic.

3. An alloy steel which is hardened by heating within the approximate temperature range of 1200 to 1800" F., containing: about 18 to 35% chromium, about 1 to 10% of metal or the group consisting of nickel and manganese, about 1 to 10% silicon, carbon up to about 4%, and the balance substantially iron in proportion to render said steel initially rerritic.

- 4. An alloy steel which is hardened by heating within the approximate temperature range 01' 1200 to 1800 F., and which is characterized by undergoing no substantial reduction in hardness after heating to temperatures as high as about 1400 F., said steel containing: about 18 to 35% chromium, about 1 to 10% of metal of the group consisting of nickel and manganese, about i to 10% silicon, not more than about 5% in aggregate of other steel alloying elements primarily for imparting other than heat hardening properties to the steel, carbon up to about 4%, and the balance all iron in proportions to render-said steel initially Ierritic.

bustion engines made of 5. An alloy steel which is hardened by heating within the approximate temperature range of 1200 to 1800 F., said steel having a hardness in excess of about 0" 32 Rockwell and undergoing no substantial reduction in hardness after heating to temperatures as high as about 1400 F.. said steel containing: about 18 to 35% chromium, about 1 to 10% of metal 01' the group consisting of nickel and manganese, about .5 to 10% silicon and about .5 to 10% oi metal of the group consisting of molybdenum and tungsten, in proportions to render said steel initially i'erritic, the content of silicon, tungsten and molybdenum aggregating about 1 to 10%.

6. An alloy steel which is hardened by heating within the approximate temperature range of 1200 to 1800 F., said steel having a hardness in excess oi about "0 32 Rockwell and undergoing no substantial reduction in hardness after heating to temperatures as high as about 1400" F., said steel containing: about 18 to 35% chromium, about 1 to 10% of metal 01' the group consisting oi nickel and manganese, and about 1 to 10% silicon, in proportions to render said steel initially terrltic.

7. A valve or valve element for internal coman alloy steel according to claim 2.

8. A valve or valve element for internal combustion engines made of an alloy steel according to claim 4.

9. A metal cutting, forming or shearing tool made of an alloy steel according to claim 2.

10. A metal cutting, forming or shearing tool made 01' an alloy steel according to claim 4.

PETER PAYSON. 

